In the field of urine analysis, etc., it has been usual to determine the number of bacteria, etc. in a sample of urine, etc. to discover inflammation and estimate the condition of a disease.
For example, a case involving an increase of bacteria in urine is diagnosed as bacteriuria, and suggests an infection of the urinary tract. Accordingly, the number of bacteria is determined for early treatment and administration of medicine.
In the field of food, etc., the number of bacteria, etc. in food are determined to see if it has not been decomposed, and in the case of fermented milk, lactic-acid beverages, etc., the determination of the number of lactic-acid bacteria in the food is performed to control it.
The determination of the number of bacteria in such cases is mainly performed by a method employing agar plate culture.
This method, however, requires expert skill and an apparatus called an incubator, and calls for 24 to 48 hours to give results.
In the case of urine analysis, for example, it is after several days that a doctor knows the results of an examination by culture of an outpatient's sample of urine which is performed in a bacteriological examination room, or center. A method for the quick determination of bacteria is desired for diagnosis of high accuracy.
Food is examined for Escherichia coli and for general bacteria, and while the results of an examination for Escherichia coli are available from 18 hours of culture, an examination for general bacteria requires 24 or more hours of culture, and the results thereof are usually available for many foods only after their shipment. An improvement has been desired for bacterial control in the determination of, among others, the number of lactic-acid bacteria in fermented milk, etc., since it usually requires about 72 hours of culture, and the number of lactic-acid bacteria is known only after the shipment of commercial products, and in many cases after consumers have drunk or eaten the products.
In the field of metal processing fluids, such as water-soluble cutting fluids, the growth of bacteria is likely to cause the decomposition of fluids. An easy culture kit (such as one sold under the tradename, "Easicult") is presently available for checking the presence of bacteria, but takes 48 hours to give results. Therefore, it is likely that the measures taken for preventing decomposition may be too late to prevent any objectionable odor from being produced by decomposition.
Moreover, there have been proposed a method of determining the enzyme activity of bacteria (Japanese Patent Application Laid-Open No. Sho 57-74095), a method using a fluorescent dye (Japanese Patent Application Laid-Open No. Sho 62-138185), a filter dyeing method (Japanese Patent Application Laid-Open No. Hei 1-124767), etc; though they are not presently employed in practice, but they have revealed drawbacks, such as the instability of a reagent used for determining enzyme activity, the necessity for a special apparatus (fluorophotometer), and the complicated operation involved in the dyeing process.
The applicant of this application has already proposed a method for determining the number of microorganisms in a sample by either dyeing the microorganisms and collecting them in a hydrophobic filter, or collecting them in a hydrophobic filter and dyeing them, washing away the excess of coloring matter and determining the number of the microorganisms in the sample from the degree of their staining, as a method overcoming the drawbacks of the prior art as stated above (Japanese Patent Application Laid-Open No. Hei 4-218392).
This method has made it possible to determine the number of microorganisms in a sample quickly and easily without requiring any highly developed skill, expert knowledge, or special equipment.
The actual use of the method has, however, revealed that it is difficult and complicated, since it requires two steps of filtering operation.
The necessity for the use of a dropper, or like device for taking a sample has also complicated the method.
It is an object of this invention to overcome the drawbacks of the prior art as stated above, and provide a method and a device which make it possible to determine the number of bacteria in a sample quickly (within one minute) and easily in a single step of filtering operation without requiring any special equipment, or expert knowledge.
It is a further object of this invention to provide a method and a kit which make it possible to determine the number of bacteria in a sample quickly (within one minute) and easily in a single step of filtering operation without requiring any special equipment, or expert knowledge, since no dropper, or like device is used for taking a sample, but a filtering operation under suction with a syringe is sufficient therefore.